Laser diode scanner with improved shock mounting

ABSTRACT

Optical alignment between components in a head of a laser scanner is maintained in the event of external shock. Optical and scanning component assemblies are shock-mounted near their respective centers of mass. A flexible, printed circuit board on which the assemblies are mounted serves as an alignment fixture.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to laser scanning systems for readingindicia having portions of different light reflectivity such as bar codesymbols and, more particularly to a lightweight, multi-component,portable laser diode scanning head supportable by a user and aimable ateach symbol to be read. Still more particularly, this invention relatesto shock mounting the heaviest components in the head at approximatelytheir respective centers of mass.

2. Description of Related Art

Various optical readers and optical systems have been developedheretofore to optically read bar code symbols printed on labels affixedto objects in order to identify the object by optically reading thesymbol thereon. The bar code symbol itself is a coded pattern comprisedof a series of bars of various widths, and spaced apart from one anotherto bound spaces of various widths, said bars and spaces having differentlight-reflecting characteristics. Such readers and systemselectro-optically decoded the coded patterns to a multiplealpha-numerical digit representation descriptive of the object. Scanningsystems of this general type, and components for use in such systems,have been disclosed, for example, in U.S. Pat. Nos. 4,251,798;4,360,798; 4,369,361; 4,387,297; 4,593,186; 4,496,831; 4,409,470;4,460,120; 4,607,156; 4,673,805; 4,736,095; 4,758,717 and 4.760,,248, aswell as in U.S. Pat. application Ser. Nos. 196,021; 7,775; 944,848;138,563; 148,48; 148,669; 148,555; 147,708 and 193,265; all of whichhave been assigned to the same assignee as the instant application andare incorporated herein to show the state of the art.

As disclosed in some of the above patents and applications, aparticularly advantageous embodiment of such a scanning system resided,inter alia, in optically modifying and directing a laser light beam froma hand-held head which was supported by a user; aiming the head and, insome cases, the laser beam itself at a symbol to be read; repetitivelyscanning the laser beam and/or the field of view of a detector acrossthe symbol; detecting the laser light reflected off the symbol duringscanning; and decoding the detected reflected light.

A drawback of known hand-held systems involves maintaining thecomponents in the head in an optically aligned relationship even afterthe head is dropped and subjected to shock. Various shock mounts haveheretofore been proposed, but a particular problem exists when a printedcircuit board is used as an alignment fixture inside the head, becausethis type of board is typically thin and flexes when subjected to shock.Such flexing disturbs the optical alignment of components associatedwith the board.

SUMMARY OF THE INVENTION 1. Objects of the Invention

It is a general object of this invention to overcome the aforementionedproblems and drawbacks of known prior art laser scanning systems.

Another object of this invention is to shock mount the heaviestcomponents in the head at approximately their centers of mass.

Still another object of this invention is to prevent a printed circuitboard used for alignment purposes from flexing and disturbing theoptical alignment when subjected to shock.

Yet another object of this invention is to provide a hand-held laserdiode scanning head which is lightweight, compact, rugged,non-wrist-and-arm fatiguing, and capable of emitting a laser beamvisible to the human eye, whereby the visible laser beam can be readilypositioned on and across close-in and far-out symbols.

A further object of this invention is to provide a laser diode scanninghead capable of reading not only symbols in contact with the head, butalso close-in and far-out symbols.

2. Features of the Invention

In keeping with these objects, and others which will become apparenthereinafter, one feature of this invention resides, briefly stated, in alaser scanning system for reading indicia having portions of differentlight reflectivity, e.g. a bar code symbol having alternating darkerbars separated by lighter spaces of variable widths. The system includesa housing, and a light source means therein for generating an incidentlaser beam. Advantageously, the light source means comprises asemiconductor laser diode which emits laser light at a wavelength ofabout 670 to about 680 nm so that the emitted laser light is at leastmarginally visible to the human eye.

Optic means are also provided in the housing, and are operative foroptically forming and directing the incident laser beam along an opticalpath toward the symbol located within a range of working distancesrelative to the housing. Laser light is reflected off the symbol. Atleast a returning portion of the reflected light travels away from thesymbol back toward the housing.

Scanning means, e.g. a scanning motor, having areciprocally-oscillatable output shaft on which a reflecting surfacesuch as a scanning mirror is mounted, are mounted in the head forscanning the symbol in a scan, and preferably at a plurality of sweepsper second across the symbol in a repetitive manner. The returningportion of the reflected laser light has a variable light intensityacross the symbol during the scan which is due, in the case of a barcode symbol, to the different light-reflective characteristics of thebars and spaces which constitute the symbol.

The system also comprises sensor means, e.g. one or more photodiodes,for detecting the variable light intensity of the returning portion ofthe reflected laser light over a field of view, and for generating anelectrical signal, typically an analog signal, indicative of thedetected variable light intensity.

Signal processing means are provided for processing the analogelectrical signal, and usually for processing the same to a digitizedelectrical signal which can be decoded to data descriptive of the symbolbeing scanned.

The scanning means is operative for scanning either the incident laserbeam itself across the symbol, or the field of view of the sensor means,or both.

Decode/control electronic circuitry is sometimes, but not always,provided on-board the housing, but may also be located remotelytherefrom. Such circuitry is operative for decoding the digitized signalto the aforementioned data, for determining a successful decoding of thesymbol, and for terminating the reading of the symbol upon thedetermination of the successful decoding thereof. The reading isinitiated by actuation of an actuator, typically a manually-actuatabletrigger means provided on the housing, and operatively connected to, andoperative for actuating, the light source means, the scanning means, thesensor means, the signal processing means, and the decode/control means.The trigger means is actuated once for each symbol, each symbol in itsrespective turn.

In a hand-held application, the housing, also called a laser scanninghead, is supported by a user in his or her hand, is aimed at each symbolto be read and, once the symbol is located, the user actuates thetrigger means to initiate the reading. The decode/control meansautomatically alerts the user when the symbol has been read so that theuser can turn his or her attention to the next symbol, and repeat thereading procedure.

One feature of this invention is embodied in preventing an opticalalignment fixture from flexing when subjected to external forces of thetype encountered when the head is dropped on the ground. The laserdiode, optical means, sensor means, and a heat sink for the diodetogether comprise an optical assembly having a center of mass. Thescanning motor is part of a scanning assembly which likewise has acenter of mass. Optical alignment between the optical and scanningassemblies is provided by a thin printed circuit board supported by, andextending between, the assemblies. Because of the thin and relativelyflexible nature of this board, two pairs of shock mounts are providedfor shock-mounting the assemblies relative to the head. Each pair ofshock mounts is aligned along an axis which extends generally through arespective center of the mass of a respective assembly. By directlyshock-mounting the assemblies to the head through their respectivecenters of mass, their heaviest components, e.g. the scanning motor andthe heat sink, will not tend to rotate about the respective axes alongwhich each pair of shock mounts is aligned. The housing will not twist,and the printed circuit board will not flex, thereby reliably ensuringthat the assemblies are retained in optical alignment.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, bestwill be understood from the following description of specificembodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a laser scanning head according to thisinvention;

FIG. 2 is a vertical sectional view taken on line 2--2 of FIG. 1;

FIG. 3 is a plan sectional view taken on line 3--3 of FIG. 2;

FIG. 4 is a front perspective view of the head of FIG. 1 in use, andschematically connected to other components of a laser scanning system;

FIG. 5 is a perspective view depicting various cross-sections of thelaser beam emitted by the head of FIG. 1;

FIG. 6 is a top plan view of part of the optical assembly of FIG. 3;

FIG. 7 is a side view of the optical assembly of FIG. 6;

FIG. 8 is an enlarged sectional view of the optical assembly of FIG. 3;and

FIG. 9 is an enlarged sectional view taken on line 9--9 of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIGS. 1-4 of the drawings., reference numeral 10generally identifies a lightweight (less than one pound), streamlined,hand-held, fully-portable, easy-to-manipulate, non-arm-and-wristfatiguing laser scanning head supportable entirely by a user for use ina laser scanning system operative for reading, scanning and/or analyzingsymbols, and aimable both prior to, and during, the reading thereof, bythe user at the symbols, each symbol in its turn. The term "symbol", asused herein, is intended to cover indicia composed of different portionshaving different light-reflective properties at the wavelength of thelight source, e.g. a laser, being utilized. The indicia may be theomnipresent Universal Product Code (UPC) symbol, or any of the black andwhite industrial symbols, e.g. Code 39, Codabar, Interleaved 2 of 5,etc.. The indicia may also be any alphabetic and/or numeric characters.The term "symbol" is also intended to cover indicia located in abackground field, wherein the indicia, or at least a portion thereof,have a different light-reflectivity property than that for thebackground field. In this latter definition, the "reading" of the symbolis of particular benefit in the fields of robotics and objectrecognition.

Turning now to FIG. 1, the head 10 includes a generally gun-shapedhousing having a handle portion 12 of generally rectangularcross-section and generally elongated along a handle axis, and agenerally horizontally-elongated barrel or body portion 11. Thecross-sectional dimension and overall size of the handle portion 12 issuch that the head 10 conveniently can fit and be held in a user's hand.The body and handle portions are constituted of a lightweight,resilient, shock-resistant, self-supporting material, such as asynthetic plastic material. The plastic housing preferably isinjection-molded, but can be vacuum-formed or blow-molded to form athin, hollow shell which bounds an interior space whose volume measuresless than a value on the order of 50 cubic inches and, in someapplications, the volume is on the order of 25 cubic inches or less.Such specific values are not intended to be self-limiting, but toprovide a general approximation of the overall maximum size and volumeof the head 10. The shell is formed of two housing parts 12a, 12bmeeting along a generally vertical joining line 12c.

As considered in an intended position of use as shown in FIG. 4, thebody portion 11 has a front prow region or nose having an inclined frontwall 11a. The body portion 11 also has a rear region or stern having arear wall 11b spaced rearwardly of the inclined front wall 11a. The bodyportion 11 also has a top wall 11c, a bottom wall 11d below the top wall11c, and a pair of opposed side walls 11e, 11f between the top andbottom walls. The front wall 11a is sloped relative to the top andbottom walls.

A manually-actuatable, and preferably depressible, trigger 13 is mountedon a cantilever resilient arm 13a for movement relative to the head in aforwardly-facing region where the handle and body portions meet andwhere the user's forefinger normally lies when the user grips the handleportion in the intended position of use. The bottom wall 11d has a loweropening, and the handle 12 has a forwardly-facing slot through which thetrigger 13 projects and is moved. The arm 13a has one end overlying atrigger switch 25 which is switched from an open to a closed state upondepression of the trigger 13.

A window 14 is stationarily mounted at the nose and islight-transmissive to allow laser light to pass from the interior to theexterior of the head, and vice versa.

A flexible, non-bulky, coil-type electrical cable 15 with multiplefreedoms of movement interconnects the head 10 to the remainder of thecomponents of the laser scanning system, whose operation is explained ingreater detail below.

A plurality of components are mounted in the head and, as explainedbelow, at least some of them are actuated by the trigger 13, eitherdirectly or indirectly, by means of a control microprocessor. One of thehead components is an actuatable laser light source (see FIGS. 3 and 4),e.g. a semiconductor laser diode 33, operative, when actuated by thetrigger 13, for propagating and generating an incident laser beam whoselight, as explained above, is at least marginally visible to the humaneye. The wavelength length of the emitted beam is in the range fromabout 670 nm to about 680 nm. The emitted laser diode beam is highlydivergent; diverges differently in different planes parallel andperpendicular to the longitudinal direction of beam propagation; isnon-radially symmetrical, i.e. anamorphic; and has a beam cross-sectionresembling an oval. The diode may be of the continuous wave or pulsetype. The diode requires a low voltage (e.g. 12 v DC or less) suppliedby a power regulator and a battery (DC) source which may be providedwithin the head, or by a re-chargeable battery pack accessory detachablymounted on the head, or by a power conductor in the cable 15 connectedto the head from an external power supply (e.g. DC source).

As best shown in FIG. 8, an optical assembly 30 is mounted in the headon a thin, flexible, printed circuit board 16 and adjustably positionedrelative to the same for optically modifying and directing the emittedlaser beam along a first optical path 21a, 21c toward a reference planewhich is located exteriorly of the head, either at the nose for readingsymbols in contact with the front wall 11a, or forwardly of the nose forreading symbols out of contact with the front wall 11a. The referenceplane lies generally perpendicular to the longitudinal direction alongwhich the emitted laser beam propagates. A symbol to be read is locatedin the vicinity of the reference plane, either at, or at one side, or atan opposite side, of the reference plane; that is, anywhere within thedepth of field of the optically modified laser beam and within a rangeof working distances as measured relative to the head. The laser beamreflects off the symbol as a specular component in one direction and asa scattered component in many directions, and that portion of thescattered laser light which travels along a second optical path 21c and21b away from the symbol back toward the head is known herein as thereturning portion which, of course, also is at least marginally visibleto the user.

As best shown in FIG. 8, the optical assembly includes an elongated,cylindrical optical tube 34 having at one end region a cylindrical borein which. an annular casing portion of the diode 33 is snugly receivedto hold the diode in a fixed position, and at the opposite end region ofthe optical tube 34 a lens barrel 35 is mounted for longitudinalmovement. The lens barrel 35 includes an aperture stop 45, blocking wallportions 44 surrounding and bounding the aperture stop, and cylindricalside wall portions 46 which bound an interior space.

The optical assembly further includes a focusing lens 32, e.g. aplano-convex lens, located within the interior space of the side wallportions 46 in the first optical path, and operative (with the stop) forfocusing the emitted laser beam at the reference plane. The aperturestop 45 may be located on either side of the lens 32, but preferably onthe downstream side. A biasing means or tensioned coil spring 47 islocated within the optical tube, and has one coil end bearing against acasing portion of the diode, and another coil end bearing against aplanar side of the lens 32. The spring constantly urges the lens againstthe blocking wall portions, thereby fixedly locating the lens relativeto the aperture stop. The lens and aperture stop are jointly moved whenthe lens barrel is longitudinally moved. The side wall portions areinitially received in a threaded or sliding relationship with an innercircumferential wall bounding the optical tube, and are thereupon fixed,e.g. by glueing or clamping, to the inner circumferential wall when adesired longitudinal spacing between the lens and the aperture stop onthe one hand, and the diode on the other hand, has been obtained. Thelongitudinal movement between the side wall portions and the innercircumferential wall of the tube constitutes an adjustable positioningmeans for the lens and the aperture stop, and the fixing in position ofthe lens and the aperture stop relative to the diode constitutes a meansfor fixedly locating the lens and the aperture stop at a predeterminedspacing from the diode.

The aperture stop has a cross-section which is, as explained below,about equal to the cross-section of the emitted laser beam at theaperture stop, thereby permitting a major portion of the emitted laserbeam to pass through the aperture stop downstream along the firstoptical path en route to the symbol. The aperture stop cross-sectionpreferably is rectangular or oval, in which case, the longer dimensionof the rectangular or oval cross-section is aligned with the largerdivergence angle of the laser beam to transmit more energy to thesymbol.

The optical assembly includes an optical block 50 having a front portion52 and a rear portion 54 together bounding an interior in which thediode 33, optical tube 34, lens barrel 35 and the aforementionedcomponents contained therein are received. A heat sink 31 is mounted inintimate thermal contact with the diode to conduct heat away from thesame. An elevation adjustment means, including at least one threadedelement 56, passes with clearance through aligned holes formedrespectively in the heat sink and the rear portion 54, and is threadedinto a threaded bore formed in the front portion 52. A hinge 58 isadvantageously realized by providing a thin, flexible, weakened zone inthe optical block between the front and rear portions thereof. The frontportion 52 is stationarily mounted on the board 16 by anchors 59. Thediode, tube, barrel and the components contained therein are mounted onthe rear portion for movement therewith. Upon turning the element 56 ineither circumferential direction about an axis along which the element56 extends, the rear portion and all the components supported thereonwill be angularly moved about the hinge 58 relative to the stationaryfront portion, thereby raising or lowering the emitted light beam whichexits the block 50 through a clearance passage 60 which is dimensionedso as not to block the beam throughout its angular range of adjustment.

The laser beam that passes through the passage 60 is directed rearwardlyby the optical assembly along path 21a within the head to a generallyplanar scanning mirror 19b for reflection therefrom. The scanning mirror19b forwardly reflects the laser beam impinging thereon along path 21cthrough the forwardly-facing, laser-light-transmissive window 14 and tothe symbol. As best shown in FIG. 5, a representative symbol 100 in thevicinity of the reference plane 102 is shown and, in the case of a barcode symbol, is comprised of a series of vertical bars spaced apart ofone another along a longitudinal direction. A laser beam spot is focusedon the symbol. When the scanning mirror is, as explained below,reciprocally and repetitively oscillated transversely to sweep the laserbeam lengthwise across all the bars of the symbol, a linear scan isgenerated. The linear scan can be located anywhere along the height ofthe bars provided that all the bars are swept. The length of the linearscan is longer than the length of the longest symbol expected to be readand, in a preferred case, the linear scan is on the order of 3 inches atthe reference plane.

The scanning mirror 19b is mounted on a scanning means, preferably ahigh-speed scanner motor 24 of the type shown and described in U.S. Pat.No. 4,387,397, the entire contents of said patent being incorporatedherein by reference and made part of the instant application. For thepurposes of this application, it is believed to be sufficient to pointout that the scanner motor 24 has an output shaft 104 on which a supportbracket 19 is fixedly mounted. The scanning mirror is fixedly mounted onthe bracket. The motor is driven to reciprocally and repetitivelyoscillate the shaft in alternate circumferential directions over arclengths of any desired size, typically less than 360°, and at a rate ofspeed on the order of a plurality of oscillations per second. In apreferred embodiment, the scanning mirror and the shaft jointly areoscillated so that the scanning mirror repetitively sweeps the laserdiode beam impinging thereon through an angular distance or arc lengthat the reference plane of about 32° and at a rate of about 20 scans or40 oscillations per second.

Referring again to FIG. 2, the returning portion of the scatteredcomponent of the reflected laser light has a variable light intensity,due to the different light-reflective properties of the various partsthat comprise the symbol 100, over the symbol during the scan. Thereturning portion of the reflected laser light is collected by agenerally concave, spherical collecting mirror 19a, and is a broadconical stream of light in a conical collecting volume centered on path21c. The collecting mirror 19a reflects the collected conical light intothe head along path 21b through a laser-light-transmissive element 106to a sensor means, e.g. a photosensor 17. The photosensor 17, preferablya photodiode, detects the variable intensity of the collected laserlight over a field of view which extends along, and preferably beyond,the linear scan, and generates an electrical analog signal indicative ofthe detected variable light intensity.

The photosensor "sees" a collection zone on the symbol. Theaforementioned angular adjustment means ensures that the emitted laserbeam impinges on the symbol at the collection zone when the laser spotimpinges on the symbol.

The collecting mirror 19a is also mounted on the support bracket 19 and,when the scanning mirror is actuated by the trigger, the collectingmirror is reciprocally and repetitively oscillated transversely,sweeping the field of view of the photodiode lengthwise across thesymbol in a linear scan.

The scanning mirror and the collecting mirror are, in a preferredembodiment, of one-piece construction, but the scanning mirror can alsobe a discrete, small, planar mirror attached by glue, or molded inplace, at the correct position and angle on a discrete, front surfaced,silvered concave mirror. The concave collecting mirror serves to collectthe returning portion of the laser light and to focus the same on thephotodiode.

Also mounted in the head are various electrical subcircuits mounted onboard 16. For example, signal processing means on board 16 are operativefor processing the analog electrical signal generated by the sensor, andfor generating a digitized video signal. Data descriptive of the symbolcan be derived from the video signal. Suitable signal processing meansfor this purpose was described in U.S. Pat. No. 4,251,798. Component 39on board 16 constitutes drive circuitry for the scanner motor, andsuitable motor drive circuitry for this purpose was described in U.S.Pat. No. 4,387,297. Component 40 on board 16 is a voltage converter forconverting the incoming voltage to one suitable for energizing the laserdiode 33. The entire contents of U.S. Pat. Nos. 4,251,798 and 4,387,297are incorporated herein by reference and made part of the instantapplication.

The digitized video signal is conducted, in one embodiment, along cable15 to decode/control means 101 (see FIG. 4) operative for decoding thedigitized video signal to a digitized decoded signal from which thedesired data descriptive of the symbol is obtained, in accordance withan algorithm contained in a software control program. The decode/controlmeans includes a PROM for holding the control program, a RAM fortemporary data storage, and a control microprocessor for controlling thePROM and RAM. The decode/control means determines when a successfuldecoding of the symbol has been obtained, and also terminates thereading of the symbol upon the determination of the successful decodingthereof. The initiation of the reading is caused by depression of thetrigger. The decode/control means also includes control circuitry forcontrolling the actuation of the actuatable components in the head, asinitiated by the trigger, as well as for communicating with the userthat the reading has been automatically terminated as, for example, bysending control signals to indicator lamps 36, 37 to illuminate thesame.

The decoded sign is conducted to a remote, host computer 103 whichserves essentially as a large data base, stores the decoded signal and,in some cases, provides information related to the decoded signal. Forexample, the host computer can provide retail price informationcorresponding to the objects identified by their decoded symbols.

In another embodiment, the decode/control means and a local data storagemeans are mounted on another printed circuit board 27 in the handleportion, and store multiple decoded signals which have been read. Thestored decoded signals thereupon can be unloaded to a remote hostcomputer. By providing the local data storage means, the use of thecable during the reading of the symbols can be eliminated -- a featurewhich is very desirable in making the head as freely manipulatable aspossible. A beeper 28 is also optionally mounted on board 27 so that theuser can hear through a port 29 in the handle when a symbol has beensuccessfully read.

The assembly at the forward end of the board 16, including the opticalblock 50, the heat sink 31, the laser diode 33 and its associatedoptics, together with the photodetector 17, has a center of mass whichapproximately extends along an axis which is co-linear with an axisalong which front shock mounts 23b, 23d extend (see FIG. 2). Theassembly at the rear end of the board 16, including the scanning motor24, the collecting and scanning mirrors on bracket 19, the arm 20, thediode 22a and receiver 22b also has a center of mass which approximatelyextends along an axis which is co-linear with an axis along which rearshock mounts 23a, 23c extend. By so positioning the heaviest componentsin the head, namely, the heat sink and the scanning motor, on, or closeto, these shock mounting axes, the tendency of the heat sink and thescanning motor to turn around the shock mounting axes is minimized,thereby resisting the tendency of the head from twisting and thetendency of the optical and scanning assemblies from moving out ofoptical alignment in the event that the head is dropped. The board 16has no support function, but serves as an alignment fixture.

The laser scanning head of FIG. 2 is of the retro-reflective typewherein the outgoing incident laser beam, as well as the field of viewof the sensor means, are scanned. It will be readily understood thatother variants also are within the spirit of this invention. Forexample, the outgoing incident laser beam can be directed to, and sweptacross, the symbol through one window on the head, while the field ofview is not scanned and the returning laser light is collected throughanother window on the head. Also, the outgoing incident beam can bedirected to, but not swept across, the symbol, while the field of viewis scanned.

The head herein need not be hand-held, but can be incorporated in adesk-top, stand-alone workstation in which the symbol is passedunderneath an overhead window or port through which the outgoing beam isdirected. Although the workstation itself is stationary during scanning,the symbol is movable relative to the workstation and must be registeredwith the outgoing beam and, for this purpose, the enhanced visibilitylaser beam described herein is advantageous. Also, the head may furtherinclude deactivation apparatus for changing the state of a surveillancedevice associated with a tag or label on which the symbol is provided,such as described in U.S. Ser. No. 236,249, assigned to the assignee ofthe instant application.

It will be understood that each of the elements described above, or twoor more together, also may find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in alaser diode scanner with improved shock mounting, it is not intended tobe limited to the details shown, since various modifications andstructural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:
 1. In a laser scanning system forreading indicia having portions of different light reflectivity, saidsystem being of the type including(A) a hand-held head normallysupportable by a user in an intended position of use; (B) an opticalassembly located in the head, having a center of mass, and including(i)laser diode for emitting a laser beam with concomitant generation ofheat, (ii) a heat sink for conducting the heat away from the diode,(iii) optic means for optically forming and modifying the laser beam tohave a predetermined beam cross-section at a reference plane in thevicinity of which indicia to be read are located and impinged by thelaser beam, thereby reflecting off the indicia reflected laser light, atleast a returning portion of which travels away from the indicia backtoward the head, and (iv) sensor means for detecting the returningportion of the reflected laser light, and for generating an electricalsignal indicative of the indicia being read; and (C) a scanning assemblylocated in the head, having a center of mass, and including(i) areciprocally oscillatable scanning motor having a drive shaft on which amirror is mounted for joint repetitive and cyclical oscillating movementa plurality of times per second, said mirror directing the laser beamtoward the reference plane and to and across the indicia to be read forscanning the same, said mirror also collecting the returning portion ofthe reflected laser light and directing the same to the sensor means,the improvement which comprises: (a) means for shock mounting theassemblies relative to the head, including(i) a first pair of shockmounts within the head and aligned along a first axis which extendsgenerally through the center of the mass of the scaning assembly, and(ii) a second pair of shock mounts within the head and aligned along asecond axis which extends generally through the center of mass of theoptical assembly; and (b) a printed circuit board supported by, andextending between, the assemblies for maintaining the assemblies inoptical alignment.
 2. The improved system as recited in claim 1, whereinthe scanning motor is the heaviest component in the scanning assemblyand is located in the vicinity of the first axis, and wherein the heatsink is the heaviest component in the optical assembly and is located inthe vicinity of the second axis.
 3. The improved system as recited inclaim 2, wherein the head has an elongated barrel having front and rearinterior regions at opposite ends of the barrel, and wherein thescanning and optical assemblies are located at respective interiorregions for better balance of the head.
 4. The improved system asrecited in claim 1, wherein the printed circuit board is a relativelythin and flexible sheet.
 5. The improved system as recited in claim 4,wherein the printed circuit board has opposite end regions, and whereinthe scanning and optical assemblies are located at respective endregions of the board.
 6. A laser scanning module, comprising:(A) anoptical assembly having a center of mass, and including(i) a laser diodefor emitting a laser beam with concomitant generation of heat, (ii) aheat sink for conducting the heat away from the diode, (iii) optic meansfor optically forming and modifying the laser beam to have apredetermined beam crosssection at a reference plane in the vicinity ofwhich indicia to be read are located and impinged by the laser beam,thereby reflecting off the indicia reflected light, at least a returningportion of which travels away from the indicia back toward the module,and (iv) sensor means for detecting the returning portion of thereflected laser light, and for generating an electrical signalindicative of the indicia being read; (B) a scanning assembly having acenter of mass, and including(i) a reciprocally oscillatable scanningmotor having a drive shaft on which a mirror is mounted for jointrepetitive and cyclical oscillating movement a plurality of times persecond, said mirror directing the laser beam toward the reference planeand to and across the indicia to be read for scanning the same, saidmirror also collecting the returning portion of the reflected laserlight and directing the same to the sensor means; (C) a printed circuitboard supported by, and extending between, the assemblies formaintaining the assemblies in optical alignment; and (D) means for shockmounting the assemblies, including(i) a first pair of shock mounts onthe board and aligned along a first axis which extends generally throughthe center of the mass of the scanning assembly, and (ii) a second pairof shock mounts on the board and aligned along a second axis whichextends generally through the center of mass of the optical assembly. 7.The improved system as recited in claim 6, wherein the scanning motor isthe heaviest component in the scanning assembly and is located in thevicinity of the first axis, and wherein the heat sink is the heaviestcomponent in the optical assembly and is located in the vicinity of thesecond axis.
 8. The improved system as recited in claim 6, wherein theprinted circuit board is a relatively thin and flexible sheet.
 9. Theimproved system as recited in claim 6, wherein the printed circuit boardhas opposite end regions, and wherein the scanning and opticalassemblies are located at respective end regions of the board.